how to retain an allocated memory

This is a discussion on how to retain an allocated memory within the C Programming forums, part of the General Programming Boards category; > already added 1 -> malloc(sizeof(strlen(src) + 1)); No, it should just be strlen(src)+1 Taking the sizeof that whole expression ...

  1. #16
    and the hat of wrongness Salem's Avatar
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    > already added 1 -> malloc(sizeof(strlen(src) + 1));
    No, it should just be strlen(src)+1

    Taking the sizeof that whole expression just reduces it to sizeof(size_t) or something like it.

    > **dest++ = *src++;
    Try something like
    char *d = *dest;

    Then use *d++ = *src++;

    What you DON'T want to do is actually move the pointer to your allocated memory.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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  2. #17
    Registered User creek23's Avatar
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    Thanks Salem! That was actually helpful. Here's the working code below.
    PHP Code:
    [code]
    #include <stdio.h>
    #include <stdlib.h>

    void my_strcpy(char **destchar *src) {
        *
    dest = (char *) malloc(strlen(src) + 1);
        
        
    char *= *dest;
        while(*
    src) {
            *
    d++ = *src++;
        }
        *
    '\0';
    }

    int main(void) {
        
    char *content1;
        
    char *content2 "hello world";
        
        
    printf("%s\n"content2);
        
        
    my_strcpy(&content1content2);
        
        
    printf("%s\n"content1);
        
        return 
    0;
    }
    [/
    code

  3. #18
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    Oh just don't forget to free() after you're done.

  4. #19
    Registered User creek23's Avatar
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    Finally wrote the function I wanted to make with help of pass-by-reference.

    The code below would allow to load a ASCII file content (hopefully with binary file too) into an uninitialized string.

    PHP Code:
    [code]
    #include <stdio.h>
    #include <stdlib.h>

    int flen(FILE *flen_file); //returns length of a file
    int fget(char **destFILE *fget_file); //returns all the content of a file
    int fload(char **dest, const char *file_name); //loads file_name into dest

    int main(void) {
        
    char *content;
        
        
    int err fload(&content"test.txt");
        
        if (
    err == 0) {
            
    printf("%s\n"content);
        }
        
    free(content);
        
        return 
    0;
    }

    int flen(FILE *flen_file) {
        
    int size;
        
        
    fseek(flen_file0SEEK_END);
            
    size ftell(flen_file);
        
    fseek(flen_file0SEEK_SET);
        
        return 
    size;
    }

    int fget(char **destFILE *fget_file) {
        
    int LOF flen(fget_file);
        
        *
    dest malloc(sizeof(char) * (LOF 1));
        
    char *= *dest;
        
    int i 0;
        while (
    LOF) {
            *
    d++ = fgetc(fget_file);
            
    i++;
        }
        *
    '\0';
        
        return 
    0;
    }

    int fload(char **dest, const char *file_name) {
        
    FILE *tmp_file fopen(file_name"rb");
        
        if (
    tmp_file != NULL) {
            if (
    fget(desttmp_file) == 0) {
                return 
    0;
            } else {
                return 
    2;
            }
        } else {
            return 
    1;
        }
    }
    [/
    code
    Now tell me those where created from random commands.

  5. #20
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    whoa, don't forget those who guided you from random crap to code.

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